The present invention relates to an artificial trachea for a trachea, and more particularly, to an artificial trachea used as a trachea substitute for the intrathoracic trachea.
In recent years, accompanying the progress made in anesthesia control and post-operative control, including operative procedure for malignant tumors of organs in the cervical and thoracic parts, there has been an increase in the number of occasions in which it is necessary to reconstitute the trachea or tracheal bifurcation.
Although the most clinically reliable reconstruction methods are direct anastomoses such as end-to-end anastomosis and end-to-side anastomosis, these methods are subject to their own restrictions on the range of reconstruction, and even within the allowed range, high-degree anastomotic techniques and relaxation sutures, etc. are required. Consequently, these procedures tend to be associated with extensive invasion. At that time, the use of a trachea substitute made of an artificial material (hereinafter to be referred to as an xe2x80x9cartificial tracheaxe2x80x9d) enables reconstruction to be performed easily and as a result, the indications for this operation can naturally be expected to be expanded.
Attempts in applying such an artificial trachea began with animal experiments conducted by Daniel, R A Jr. (published in J. Thorac. Surg. 17, 335 (1948) xe2x80x9cThe Regeneration of Defects of the Trachea and Bronchixe2x80x9d), and although various materials have been attempted to be used since that time, no artificial materials that can be sued safely in the clinical application have been still developed with the exception of partial prosthesis of the cervical trachea.
In the case of artificial trachea for the intrathoracic trachea for which there is the greatest desire for clinical effectiveness in particular, differing from replacement of the cervical trachea in which the artificial trachea is densely covered by surrounding tunica muscularis following replacement, since the artificial trachea is subjected to poor conditions in which there is little support and continuously subjected to the application of external force, in addition to common problems confronting artificial trachea in the form of providing adequate support and rapid and reliable incorporation in the body with little inflammatory reaction, countermeasures against leakage of air constitute the most serious problem.
In order to improve the situation as described above, the object of the present invention is to provide an artificial trachea that is able to be used safely in the clinical application, and especially an artificial trachea for the intrathoracic trachea.
The present invention is an artificial trachea which comprises a polypropylene mesh tube 21 for the base material, around the outer periphery of which a polypropylene filamentous stent 22 is wound in a spiral shape, an amorphous collagen thin layer 30 formed on the surface of said base material, and a fine fibrous collagen layer 20 formed on the inner and outer surface of said amorphous collagen thin layer, to which thermal dehydration crosslinking is performed. (A simplified drawing of the overall constitution is shown in FIG. 1. Furthermore, in the drawing, although those members indicated with reference numerals 21, 22 and 30 should be indicated as being cross-sections with diagonal lines, such diagonal lines are omitted due to their complexity.)
Here, the thin layer formed on the surface of the base material not only covers the surface of the mesh units constituting the mesh tube, but also obstructs the pores in the mesh and covers the surface of the filamentous stent.
In addition, the amorphous collagen layer refers to a collagen layer having an amorphous structure in which collagen molecules are irregularly dispersed in the monomer and oligomer states.
Moreover, as shown in FIG. 2, the fine fibrous collagen layer refers to that in which ultrafine fibers 15 having a diameter of about 5 nm and composed of several collagen molecules serve as the basic unit for forming fine fibers 14 having a diameter of about 50 nm, these then form narrow fibers 13a and 13b having a diameter of about 2 xcexcm, said narrow fibers then alternately overlap in the manner of weft and warp to form fibers 12 having a diameter of about 6 xcexcm, these fibers then overlap in the coaxial direction to form plate-like fibers 11 having a diameter of about 20-50 xcexcm, and said plate-like fibers are dispersed in the form of a non-woven fabric (see reference numeral 20). The overall constitution of this layer is shown in FIG. 3.
Furthermore, the above artificial trachea is suitable for use as an intrathoracic trachea, and particularly as a trachea substitute for the tracheal bifurcation. Furthermore, it can naturally also be used as a trachea substitute for the cervical trachea based on the degree of difficulty of that application.